/*
 * riggerd/riggerd.c - implementation of dnssec-trigger daemon
 *
 * Copyright (c) 2011, NLnet Labs. All rights reserved.
 *
 * This software is open source.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 * 
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * Neither the name of the NLNET LABS nor the names of its contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * \file
 * Implementation of dnssec-trigger daemon.
 */

#include "config.h"
#include "log.h"
#include "cfg.h"
#include "svr.h"
#include "reshook.h"
#include "netevent.h"
#ifdef HAVE_GETOPT_H
#include <getopt.h>
#endif
#include <signal.h>
#include <fcntl.h>
#ifdef HAVE_OPENSSL_ENGINE_H
#include <openssl/engine.h>
#endif
#ifdef HAVE_OPENSSL_CONF_H
#include <openssl/conf.h>
#endif
#ifdef USE_WINSOCK
#include "winrc/netlist.h"
#include "winrc/win_svc.h"
#endif
#ifdef HOOKS_OSX
#include "osx/wakelist.h"
#endif

/** print usage text */
static void
usage(void)
{
	printf("usage:  dnssec-triggerd [options]\n");
	printf(" -h		this help\n");
	printf(" -v		increase verbosity\n");
	printf(" -d		do not fork into the background\n");
	printf(" -c file	config file, default %s\n", CONFIGFILE);
	printf(" -u		uninstall the dns override on the system\n");
	printf("		makes resolv.conf mutable again.\n");
#ifdef USE_WINSOCK
	printf("-w opt  windows option: \n");
	printf("        install, remove, start, stop - manage the service\n");
	printf("        waitstop - wait for svc to stop (-c servicename)\n");
	printf("        service - used to start from services control panel\n");
#endif
}

/** variable to signal if we need to reload */
static sig_atomic_t sig_reload = 0;

/** sighandler.  Since we must have one
 *  * @param sig: signal number.
 *   * @return signal handler return type (void or int).
 *    */
static RETSIGTYPE record_sigh(int sig)
{
	switch(sig) {
#if defined(SIGCHLD) && defined(HOOKS_OSX)
	case SIGCHLD:
		if(1) {
			int status = 0;
			pid_t p;
			/* waitpid for the ended process we forked at start,
			 * so that it does not turn into a zombie */
			while( (p=waitpid(-1, &status, WNOHANG)) > 0) {
				verbose(VERB_ALGO, "child proc %d exited %d",
					(int)p, (int)WEXITSTATUS(status));
			}
			if(p == -1 && errno != ECHILD)
				log_err("waitpid: %s", strerror(errno));
		}
		break;
#endif
#ifdef SIGHUP
	case SIGHUP:
		sig_reload = 1;
		/* fall through and exit commbase with reload boolean set */
#endif
	case SIGTERM:
#ifdef SIGQUIT
	case SIGQUIT:
#endif
#ifdef SIGBREAK
	case SIGBREAK:
#endif
	case SIGINT:
		if(global_svr)
			comm_base_exit(global_svr->base);
		else fatal_exit("killed by signal %d", (int)sig);
	break;
#ifdef SIGPIPE
	case SIGPIPE:
	break;
#endif
	default:
		log_err("ignoring signal %d", sig);
	}
}

#ifdef HOOKS_OSX
static void
osx_probe_hook(void)
{
	int s;
	pid_t pid = fork();
	switch(pid) {
	default: 	/* main */
		return;
	case -1:
		/* error */
		log_err("cannot fork: %s", strerror(errno));
		return;
	case 0:
		/* child */
		break;
	}
	/* same value as in script - cause reprobe */
	unlink("/tmp/dnssec-trigger-osx.tmp");
	if((s=system(LIBEXEC_DIR"/dnssec-trigger-osx.sh")) == -1)
		log_err("cannot exec dnssec-trigger hook osx %s",
			strerror(errno));
	else exit (WEXITSTATUS(s));
	exit (0);
}
#endif /* HOOKS_OSX */

/** store pid in pidfile */
static void
store_pid(char* pidfile)
{
	FILE* f;
	if(!pidfile || pidfile[0]==0)
		return;
	f = fopen(pidfile, "w");
	if(!f) fatal_exit("could not write pid %s: %s",
		pidfile, strerror(errno));
	if(fprintf(f, "%u\n", (unsigned)getpid()) < 0)
		fatal_exit("could not write pid %s: %s",
			pidfile, strerror(errno));
	fclose(f);
}

/** delete pidfile */
static void
unlink_pid(char* pidfile)
{
	int fd;
	/* truncate pidfile */
	fd = open(pidfile, O_WRONLY | O_TRUNC, 0644);
	if(fd != -1)
		close(fd);
	unlink(pidfile);
}

/** detach from command line */
static void
detach(void)
{
#if defined(HAVE_DAEMON) && !defined(DEPRECATED_DAEMON)
	/* use POSIX daemon(3) function */
	if(daemon(1, 0) != 0)
		fatal_exit("daemon failed: %s", strerror(errno));
#else /* no HAVE_DAEMON */
#ifdef HAVE_FORK
	int fd;
	/* Take off... */
	switch (fork()) {
		case 0:
			break;
		case -1:
			fatal_exit("fork failed: %s", strerror(errno));
		default:
			/* exit interactive session */
			exit(0);
	}
	/* detach */
#ifdef HAVE_SETSID
	if(setsid() == -1)
		fatal_exit("setsid() failed: %s", strerror(errno));
#endif
	if ((fd = open("/dev/null", O_RDWR, 0)) != -1) {
		(void)dup2(fd, STDIN_FILENO);
		(void)dup2(fd, STDOUT_FILENO);
		(void)dup2(fd, STDERR_FILENO);
		if (fd > 2)
			(void)close(fd);
	}
#endif /* HAVE_FORK */
#endif /* HAVE_DAEMON */
}

/** do main work of daemon */
static void
do_main_work(const char* cfgfile, int nodaemonize, int verb)
{
	struct cfg* cfg;
	struct svr* svr;
	/* start signal handlers */
	if( signal(SIGTERM, record_sigh) == SIG_ERR ||
#ifdef SIGQUIT
		signal(SIGQUIT, record_sigh) == SIG_ERR ||
#endif
#ifdef SIGBREAK
		signal(SIGBREAK, record_sigh) == SIG_ERR ||
#endif
#ifdef SIGHUP
		signal(SIGHUP, record_sigh) == SIG_ERR ||
#endif
#ifdef SIGPIPE
		signal(SIGPIPE, SIG_IGN) == SIG_ERR ||
#endif
#if defined(SIGCHLD) && defined(HOOKS_OSX)
		signal(SIGCHLD, record_sigh) == SIG_ERR ||
#endif
		signal(SIGINT, record_sigh) == SIG_ERR
	)
		log_err("install sighandler: %s", strerror(errno));
	/* start daemon */
	cfg = cfg_create(cfgfile);
	verbosity += verb;
	if(!cfg) fatal_exit("could not create config");
	svr = svr_create(cfg);
	if(!svr) fatal_exit("could not init server");
	log_init(cfg->logfile, cfg->use_syslog, cfg->chroot);
	if(!nodaemonize)
		detach();
	store_pid(cfg->pidfile);
	log_info("%s start", PACKAGE_STRING);
	/* start 127.0.0.1 service (assumes not left in insecure mode),
	 * unbound starts in authority-direct mode by default */
	/* TODO: check if already localhost and if so do not provide a small
	 * window of opportunity here */
	hook_resolv_localhost(cfg);
#ifdef USE_WINSOCK
	netlist_start(svr);
#endif
#ifdef HOOKS_OSX
	osx_probe_hook();
	osx_wakelistener_start(cfg);
#endif
	while(1) {
		svr_service(svr);
		if(sig_reload) {
			struct cfg* c2;
			verbose(VERB_OPS, "%s reload", PACKAGE_STRING);
			if(!(c2 = cfg_create(cfgfile)))
				log_err("could not reload config");
			else {
				cfg_delete(cfg);
				cfg = c2;
				svr->cfg = cfg;
			}
			/* reopen log after HUP to facilitate log rotation */
			if(!cfg->use_syslog)
				log_init(cfg->logfile, 0, cfg->chroot);
			sig_reload = 0;
			continue;
		}
		break;
	}
	/* attempt to set 127.0.0.1 in case we weren't, for next reboot,
	   so that during the reboot there is no window of opportunity */ 
	if(svr->insecure_state)
		hook_resolv_localhost(cfg);
	unlink_pid(cfg->pidfile);
	log_info("%s stop", PACKAGE_STRING);
	svr_delete(svr);
	cfg_delete(cfg);
}

/** getopt global, in case header files fail to declare it. */
extern int optind;
/** getopt global, in case header files fail to declare it. */
extern char* optarg;

/**
 * main program. Set options given commandline arguments.
 * @param argc: number of commandline arguments.
 * @param argv: array of commandline arguments.
 * @return: exit status of the program.
 */
int main(int argc, char *argv[])
{
	int c;
	const char* cfgfile = CONFIGFILE;
	int nodaemonize = 0, verb = 0, uninit_it = 0;
	const char* winopt = NULL;
#ifdef USE_WINSOCK
	int cmdline_cfg = 0;
	int r;
	WSADATA wsa_data;
	r = WSAStartup(MAKEWORD(2,2), &wsa_data);
	if(r != 0) {
		fatal_exit("could not init winsock. WSAStartup: %s",
			wsa_strerror(r));
	}
#endif /* USE_WINSOCK */

	log_ident_set("dnssec-triggerd");
	log_init(NULL, 0, NULL);
	while( (c=getopt(argc, argv, "c:dhuvw:")) != -1) {
		switch(c) {
		case 'c':
			cfgfile = optarg;
#ifdef USE_WINSOCK
			cmdline_cfg = 1;
#endif
			break;
		case 'u':
			uninit_it = 1;
			break;
		case 'v':
			verbosity++;
			verb++;
			break;
		case 'w':
			winopt = optarg;
			break;
		case 'd':
			nodaemonize=1;
			break;
		default:
		case 'h':
			usage();
			return 1;
		}
	}
	argc -= optind;
	argv += optind;
	if(argc != 0) {
		usage();
		return 1;
	}

	ERR_load_crypto_strings();
	ERR_load_SSL_strings();
	OpenSSL_add_all_algorithms();
	(void)SSL_library_init();

	if(uninit_it) {
		struct cfg* cfg = cfg_create(cfgfile);
		if(!cfg) fatal_exit("could not create config");
		hook_resolv_uninstall(cfg);
	} else if(winopt) {
#ifdef USE_WINSOCK
		wsvc_command_option(winopt, cfgfile, verb, cmdline_cfg);
#else
		fatal_exit("option not supported");
#endif
	} else {
		do_main_work(cfgfile, nodaemonize, verb);
	}
	EVP_cleanup();
#ifdef HAVE_OPENSSL_ENGINE_H
	ENGINE_cleanup();
#endif
#ifdef HAVE_OPENSSL_CONF_H
	CONF_modules_free();
#endif
	CRYPTO_cleanup_all_ex_data();
	ERR_remove_state(0);
	ERR_free_strings();
	RAND_cleanup();

#ifdef USE_WINSOCK
	if(WSACleanup() != 0) {
		log_err("Could not WSACleanup: %s",
			wsa_strerror(WSAGetLastError()));
	}
#endif
	log_init(NULL, 0, NULL); /* close logfile */
	return 0;
}